TECHNICAL COMPARISON AND EVALUATION OF A PUMPED THERMAL ENERGY STORAGE WITH TWO DIFFERENT DESIGNS

Abstract

Increased worldwide demand for energy (especially electricity), rising energy costs, and heightened environmental concerns are factors that continually press for the adoption of technologies to exploit renewable energy sources (RES). In order to adopt these systems, large-scale energy storage systems are needed to ensure the security of supply in energy systems due to the increasing share of renewable energy sources in the energy mix. The paper proposes a new form of energy storage technology that utilizes a combination of a heat pump and an organic Rankine cycle, referred to as Carnot Batteries (CB), which can store thermal energy for several hours to a few days and transform it back to electrical energy. Two different configurations of Carnot Batteries were tested using models created in Matlab programming software, with six working fluids used for technical optimization. The second, more complex configuration increased the roundtrip efficiency mainly due to the better performance of the two-stage heat pump.